1. Field of the Invention
The present invention generally relates to switch devices, and more particularly to a switch device of a communication system which provides services of relaying cells or packets on demand.
A switch device of this type provides an on-demand cell relay service or a switched virtual call service (SVC service) which is an on-demand frame relay service.
In the SVC service, a call set-up/release process is carried out between a calling terminal and a called terminal by a pre-event/post-event signaling control according to a layer-3 communication protocol. In this case, there is no problem when the call set-up/release process is normally performed. If a fault occurs in a user terminal, a line (channel) or a switch device, the call process will no longer controlled and managed normally, and an incompatibility of the state of the call will occur between the user terminal and the switch device. It is thus desired that a switch device be provided which can easily release the incompatibility of the call state.
2. Description of the Related Art
FIG. 1 is a block diagram of a conventional ATM (Asynchronous Transfer Mode) switch system, which includes user terminals 1a and 1b, line (channel) termination equipments 2a and 2b, an ATM switch (ATMSW) 3, a signaling controller 4 which terminates a signaling link, and a main controller 5. An ATM switch device includes the line termination devices 2a and 2b, the signaling controller 4 and the main controller 5.
The user terminals 1a and 1b and the ATM switch device are coupled together via physical links, via which logical data paths are set and released between the user terminals 1a and 1b and the ATM switch device. The setting and releasing of the data paths are carried out by a signaling control using the signaling links. The signaling control is realized by providing the ATM switch device and the user terminals 1a and 1b with a layer-3 communication control function which conforms with respective specific layer-3 communication protocols.
The main controller 5 includes a processor part CC, and a main memory part MM. The processor part CC has a main function of realizing various communication services. The main memory part MM stores various pieces of data for controlling. The processor part CC includes a layer-3 communication controller 6. The main memory part MM includes a connection management table, a subscriber (user) data table, a line termination equipment information (identification number) table, and a call process management table.
The subscriber data table includes, for each subscriber, the telephone number and information concerning various communication services. The line termination equipment information table includes translation information used to obtain a number of the related line termination equipment 2 from a number SN of the signaling controller 4 and a port number PN of the corresponding signaling link. The translation information is generated by a command when a user terminal request the SVC service, and is stored in the line termination equipment information table. Further, the translation information is sent to the signaling controller 4 when it is generated, and is stored in a memory (not shown) therein.
When the SVC service is presented, the information concerning the connection used as a signaling link is presented in the same manner as the translation information, and the connection for the signaling link is supplied between the user terminal and the ATM switch device. The connection information for the signaling link is managed by specific data so that it can be searched for by the signaling controller number SN and the part number PN.
The information concerning a connection (data path) used in the SVC service is managed, for each service application, using the connection management table of the layer-3 communication controller 6. The service application includes a permanent virtual circuit (PVC) and a switched virtual call (SVC). When an inquiry request for the connection information is generated within the ATM switch device or from the outside thereof, the request source can be notified of the connection information VPI/VCI for each service application PVC/SVC. The above connection management process can inform the service application PVC/SVC by receiving the connection information VPI/VCI.
With the above structure, when a data path is set between the user terminals on demand, the signaling controller 4 of the ATM switch device receives information concerning a signaling related to the SVC service and sent by the user terminal. The received information is modified so that the signaling controller number SN and the port number PN which terminates the signaling link are added thereto, and is sent to the layer-3 communication controller 6.
The layer-3 communication controller 6 searches the line termination equipment table by referring to the signaling controller number SN and the part number PN, and obtains the corresponding line termination equipment number CN presented to the subscribers, and refers to the subscriber data table by using the obtained line termination equipment number CN. Then, the controller 6 obtains subscriber data of the subscriber accommodated in the ATM switch device, and controls the SVC service according to the subscriber information in the subscriber data.
However, the above conventional scheme has the following disadvantages. There is a possibility that a fault may occur in the ATM switch device while the service is provided. Examples of such a fault are faults occurring the line, the signaling link, the signaling controller 4, the ATM switch, the processor part CC/main memory part MM (which may require a restart of the ATM switch), and a controller which specifically deals with the protocol such as the layer-3 communication controller. If a fault as described above occurs, a communication between the ATM switch device and the user terminal will be interrupted. Even if the fault is removed and the system restarts, the control of the correct SVC service will not be ensured. If a fault which does not ensure the restarting or the call process in a defective device occurs in the ATM switch device, the ATM switch device releases the relating call by itself. However, there is no method to ensure that the user terminal will be correctly notified of the call releasing procedure carried out in response to the occurrence of a fault. Hence, there is a possibility that an incompatibility may occur between the call process in the ATM switch device and the call process in the user terminal. Such a situation may occur if a fault occurs in the user terminals.
It is a general object of the present invention to eliminate the above disadvantages.
A more specific object of the present invention is to provide a switch device which efficiently eliminate an incompatibility regarding the call process which occurs between the user terminals and the switch device.
The above objects of the present invention are achieved by a switch device in a communication system in which a relay service of a cell or packet is provided on demand, the switch device comprising: a layer-3 communication controller which performs a signaling control of a call set-up/release requested by a user terminal in accordance with a layer-3 communication protocol; and a layer-3 communication restart controller which can be connected to the user terminal in accordance with the layer-3 communication protocol and is connected to controllers in the switch device via a given interface. The layer-3 communication restart controller perform a call release process for a call managed by the layer-3 communication controller in accordance with a restart request for a call from the user terminal, and requests a call restart process to the user terminal in accordance with a call release process issued in the switch device.
The switch device may be configured so that: the layer-3 communication restart controller includes a compatibility controller interposed between the user terminal and the switch device; and when the compatibility controller receives, from the user terminal, a response to the restart request from the layer-3 communication restart controller, the compatibility controller determines whether a content of the response coincides with a content of the restart request issued by the layer-3 communication restart controller, and accepts the restart request if a determination result is affirmative.
The switch device may be configured so that: the layer-3 communication restart controller includes a compatibility controller interposed between the user terminal and the switch device; and when the compatibility controller receives the restart request from the user terminal, the compatibility controller determines whether the restart request includes necessary information or whether information contained in the restart request is acceptable in the layer-3 communication restart controller; and the compatibility controller accepts the restart request if a determination result if affirmative.
The switch device may be configured so that: the layer-3 communication restart controller includes a connection analysis controller interposed between the user terminal and the switch device; when the connection analysis controller receives the restart request from the user terminal, the connection analysis controller determines whether information concerning a connection included in the restart request indicates an intolerable connection, and accept the restart request if a determination result is negative.
The switch device may be configured so that the connection analysis controller selectively makes a first decision to a permanent virtual circuit, a second decision to a signaling link, and/or a third decision to the permanent virtual circuit and the signaling link.
The switch device may be configured so that: the layer-3 communication restart controller includes a protection controller interposed between the user terminal and the switch device, and a process state management controller which holds user notification restart process management information used to manage the restart process executed by the switch device and directed to the user terminal in response to the restart request from the user terminal; and when the protection controller receives the restart request from the user terminal, the protection controller determines whether the restart process is being executed in response to another restart request from the user terminal by searching the user notification restart process management information in the process state management part, and accepts the restart request if a determination result is negative.
The switch device may be configured so that: the layer-3 communication restart controller includes a protection controller interposed between the user terminal and the switch device, and a process state management part which holds user notification restart process management information used to manage the restart process executed by the switch device and directed to the user terminal in response to the restart request from the user terminal; and when the protection controller receives the restart request from one of the controllers in the switch device, the protection controller determines whether the user terminal is executing the restart process by searching the switch device notification restart management information in the process state management part, and accepts the restart process if a determination result is negative.
The switch device may be configured so that, when a counter determination result is obtained, the response or the restart request is discarded and the user terminal is notified that the response or the restart request is discarded and that the response or the restart request has a departure (error).
The switch device may be configured so that, when the determination result is affirmative, the protection controller discards the restart request, holds and executes all restart requests in a requesting order, or executes a restart request which is held for the last time after the restart process being executed is completed.
The switch device may be configured so that an operation of the protection controller to be executed when the determination result is affirmative can be selected by the user terminal.
The switch device may be configured so that: the layer-3 communication controller includes a layer-3 restriction controller which is connected to the layer-3 communication restart controller and restricts a call process operation of the layer-3 communication controller on the basis of a restart process state of the layer-3 communication restart controller; and the layer-3 restriction controller restricts a layer-3 communication sequence which is executed by the layer-3 communication controller and is directed to the user terminal which is executing the restart process in response to the restart process of the layer-3 communication restart controller.
The switch device may be configured so that: the layer-3 communication controller includes a call restriction controller which is connected to the layer-3 communication restart controller and restricts a call process operation of the layer-3 communication controller on the basis of a restart process state of the layer-3 communication restart controller; and when the layer-3 communication controller receives a call set-up request from the user terminal and a connection captured by the layer-3 communication controller is a connection which is subjected to the restart process by the layer-3 communication restart controller, the call restriction controller restricts the call set-up request.
The switch device may be configured so that: the layer-3 communication restart controller includes a selection controller which holds information concerning a control type given by the user terminal beforehand, the control type including a network-initiative control, a user-initiative control and a two-way control; and when the layer-3 communication restart controller receives the restart request from the user terminal or one of the controllers in the switch device, the layer-3 communication restart controller determines whether the restart process should be executed in accordance with the information concerning the control type held in the selection controller.
The switch device may be configured so that, when the restart request from the user terminal is received, the selection controller determines whether the restart request is inconsistent with the control type given by the user terminal, and notifies, if a determination result is affirmative, the user terminal of an inconsistency of the restart request.
The switch device may be configured so that: the layer-3 communication restart controller includes a preservation controller connected to a system management control part which manages the controllers in the switch device, and a control memory management part which holds process state management information for managing a state transition of the restart process in the layer-3 communication restart controller; and when the preservation controller receives a notification of a restart from the system management control part, the preservation controller extracts a call which is subjected to the restart process by the layer-3 communication restart controller by searching the process state management information of the control memory management part, and executes the restart process for the call if ensuring the restart process is requested.
The switch device may be configured so that the layer-3 communication restart controller includes: a preservation controller connected to a system management control part which manages the controllers in the switch system; a control memory management part which holds process state management information for managing a state transition of the restart process in the layer-3 communication restart controller; and a process state management part which holds user notification restart process management information used to manage the restart process executed by the switch device and directed to the user terminal in response to the restart request from the user terminal, and wherein: when the preservation controller receives a notification of a restart from the system management controller, the preservation controller extracts a call which is subjected to the restart process by the layer-3 communication restart controller by searching the process state management information of the control memory management part on the basis of the restart process management information of the process state management part, and executes the restart process for the call if ensuring the restart process is requested.
The switch device may be configured so that ensuring the restart process is selectable beforehand in accordance with the type of the restart.
The switch device may be configured so that: the layer-3 communication restart controller includes an enquiry controller interposed between a lower layer controller and the switch device; and if the enquiry controller detects a link reset/interlink fault in a signaling link, or if the enquiry controller receives a notification of a fault relating to the lower layer, the enquiry controller obtains a call process state of a call which encounters a fault from a call process management table managed by the layer-3 communication controller, and enquries of user terminal a state of the call which encounters the fault via the layer-3 communication controller in order to confirm whether the layer-3 communication sequence is normally executed by the layer-3 communication controller.
The switch device may be configured so that: the layer-3 communication restart controller includes an enquiry controller interposed between a lower layer controller and the switch device; and if the enquiry controller detects a link reset/interlink fault in a signaling link, or if the enquiry controller receives a notification of a fault relating to the lower layer, the enquiry controller obtains a call process state of a call which encounters a fault from a call process management table managed by the layer-3 communication controller, and enquries, by itself, of the user terminal a state of the call which encounters the fault in order to confirm whether the layer-3 communication sequence is normally executed by the layer-3 communication controller.
The switch device may be configured so that: the layer-3 communication restart controller includes an announcement controller interposed between a lower layer controller and the switch device; and when the layer-3 communication restart controller receives the restart request from the user terminal and detects a situation in which a resource necessary for the restart control cannot be obtained or a process inconsistency occurs in the layer-3 communication restart controller, so that the restart process cannot continue, the announcement controller notifies the user terminal which issues the restart request that the restart process is stopped.
The switch device may be configured so that: the layer-3 communication restart controller includes a restart control sequence control interface controller which provides a layer-3 communication restart control sequence interface with the user terminal, and a reject controller connected to the restart control sequence control interface controller; when the restart control sequence control interface controller receives the restart request from the user terminal, the restart control sequence control interface controller checks a format of the received restart request, and provides the reject controller with an analysis result and necessary received information; and the reject controller discards the restart request in response to receipt of the analyses result and the necessary received information, and edits given notification information based thereon, the given notification information being sent to the user terminal.
The switch device may be configured so that: the layer-3 communication restart controller includes a notification controller interposed between the layer-3 communication restart controller and an upper-layer controller or the layer-3 communication controller; the notification controller is activated when there is no response from the user terminal in response to the restart request from the layer-3 communication restart controller, and edits abnormality control on the basis of abnormality information concerning a line, a logical path or a logical connection via which no response is received; and the notification controller notifies a maintenance person of the abnormality information, or notifies the layer-3 communication controller of the abnormality information in order to urge a restriction of the call process to the user terminal.
The switch device may be configured so that a range of the restriction of the call process by the layer-3 communication controller is selectable beforehand by the user terminal.
The switch device may be configured so that the layer-3 communication controller releases the restriction of the call process when the user terminal which restricts the call process activates the layer-3 communication controller.
The switch device may be configured so that the connection which is subject to the call process is recovered when the user terminal specifies the above connection and activates the layer-3 communication controller.
The switch device may be configured so that: the layer-3 communication restart controller includes an overload controller connected to a system management control part which manages the controllers of the switch device; when the overload controller receives, from the system management controller, a notification of a congestion which occurs in the switch device, the overload controller analyzes a content of the notification and manages an analyzed result for each congestion type; and the overload controller provides congestion management information in response to an enquiry from the layer-3 communication restart controller.
The switch device may be configures so that: the layer-3 communication restart controller includes an upper-layer interface controller connected to an upper-layer controller; and the layer-3 communication restart controller executes the restart process in a switch initiative formation in response to a command that is input via the upper-layer interface controller.
The switch device may be configured so that: the layer-3 communication restart controller includes an upper-layer interface controller connected to the layer-3 communication controller; and when there is no release response from the user terminal by a call release request by the layer-3 communication controller, the layer-3 communication restart controller is informed that there is no release response and executes the restart process in a switch initiative formation.
The switch device may further comprise: administration controller that are respectively provided to the controllers of the switch device and supervise operating states of the controllers; and a main administration controller which totally manages the administration controllers, wherein the main administration controller collects supervisory information from the controllers and issue an indication when the supervisory information satisfies a given condition.